Sheet metal forming parts as a rule are manufactured by deep-drawing. The semi-finished parts, the so-called sheet metal blanks or billets, for this purpose are placed in multi-stage forming tools. By means of presses, in which the forming tools are mounted, the parts are formed. The parts as a rule are manufactured out of a flat sheet metal billet in several forming stages by means of processing stages such as drawing, restriking, flanging, etc., in combination with cutting stages.
The design and dimensioning of the forming tools is an iterative process, involving the modeling of the geometry of forming parts in different stages of the processing, and of corresponding tools. The term “geometry” in the present context stands for a (computer readable) representation of the geometrical dimensions of a body, for example, in the form of a finite elements grid, or of a quantity of parameterized elemental bodies and/or surfaces.
In this manner a process layout or method plan is developed, which among others describes a sequence of part geometries to be produced. The method plan or process layout as a rule also describes an allocation of individual forming operations to the part geometries.
U.S. Pat. No. 7,885,722 discloses a computer based method for generating a method plan for the manufacture of sheet-metal forming parts by way of forming processes in a series of (process) operations. The method involves the steps of                determining a set of geometry features (hereinafter also just called “features”) of a part in a geometry model of the part, wherein each of the geometry features is described by a feature type and by way of geometric parameters for describing the geometric shape of the geometry feature; and        determining an associated method standard for each of the geometry features, wherein a method standard describes one variant for manufacturing the respective geometry feature, the selection of the method standards which may be associated with a certain geometry feature is dependent on the feature type of the geometry feature, and wherein a method standard comprises at least one module, and a module represents a processing unit and describes which machining unit may be implemented within an operation (or process operation).        
U.S. Pat. No. 8,140,306 discloses a method in which so-called geometry operators associate a geometry of an area of a first geometry model with a geometry of an area of a second geometry model, and describe a transition from one of these two associated geometries to the other one. Each geometry operator can be associated with a (process) operation.
There is a need for providing a way for displaying and manipulating the relations between the entities involved in the definition of a method plan. There also is a need for efficiently assisting a user in the definition and iterative improvement of a method plan.
Many of the embodiments described herein are generally directed to a method and computing system for designing a sheet-metal-forming process of the type mentioned initially, which assists a user in creating a method plan for the manufacture of sheet-metal parts.
The following terms are used: parts are manufactured by way of forming presses, which may be implemented as single station presses (combined to form a tandem press line) or as a multiple station press, that is, a press with multiple stations (in a progressive tool or in a transfer tool). A press with multiple stations comprises several individual stations wherein several operations are accomplished with each press stroke. In each station and at each stroke of the press one or more manufacturing steps are effected on the part, after which the part is moved to the next station. Multiple station presses or dies can be of two types: progressive and transfer. With progressive dies, coil stock is fed into the press. Individual stampings are connected with a carrier strip as they progress through the various die operations and are ultimately separated and then discharged from the press. In transfer die operations individual stock blanks are mechanically moved from die station to die station within a single die set.
Each stroke of a single, separate press in a tandem press line shall be called one operation (or process operation) of the press on the part. In the case of a press with multiple stations, one stroke of the press shall be defined to comprise one process operation per station. In other words, the term “process operation” stands for one stroke of a single station press or for one stroke of the press in one station of a multiple station press. A process operation comprises the manufacturing steps effected on the part in one station, after it is moved into the station and before it is moved out of the station.
One process operation comprises one or more manufacturing steps effected on the part. Typically, manufacturing steps are associated with and assigned to a feature of the finished part, and one or more manufacturing steps are needed to manufacture a particular feature.
From the point of view of the part, a feature is manufactured by a manufacturing sequence of individual manufacturing steps. Those manufacturing steps for a feature which are carried out in the same station, that is, in the same process operation, shall hereinafter be called a processing unit, or simply a “module”. As described in abovementioned U.S. Pat. No. 7,885,722, features can be manufactured in different ways, that is, using different modules or combinations of modules. For example, a feature created by cutting and punching can be manufactured by two separate modules, one module comprising one manufacturing step “cutting” and the other module comprising one manufacturing step “punching”. Alternatively, the feature can be manufactured by a single module that comprises one manufacturing step “cutting” and another manufacturing step “punching”, executed in the same process operation. The physical realization of a processing unit is done by a tool. The term “tool” on the one hand can refer to typically a punch and die as a whole, and also—depending on context—a region or a particular component of the punch and die that are involved in shaping a particular feature. Such a “local” tool can be, for example, a piercing punch, piercing die, trim steel, flanging steel, etc. . . . .
When the present application mentions a processing unit being assigned to a tool, this usually means that the processing unit is assigned to such a “local” tool. For example, several processing units that each correspond to the piercing of a hole can be assigned to a single cam. Then the cam including all necessary components is the tool that manufactures these several holes in one process operation.
Regions on the part which typically are manufactured after the deep drawing in further operations, have geometric properties which differentiate them from the rest of the geometry. Such regions, are herein called geometry features or simply features, They can be, for example, of one of the following feature types: holes, openings, punchings (piercings), backdrafted (undercut) regions, flanges, postforming regions, edge regions etc. Features can also be shaped in the deep drawing operation.
A working direction is a direction in 3D space in which a tool moves. The working direction can be represented by a vector in 3D space. The tool typically is a punch or a cam. A working angle is an angle at which a tool meets the part. Working angles are usually classified as shear angle, trim angle, and backdraft angle. Working angles are defined relative to a working direction. In the design phase, working directions can be used that do not correspond to a specific tool (because the tool has not yet been selected or defined). A working direction that serves as a reference for one or more working angles can be called a reference working direction.
An important part of a method plan is the association of processing units with process operations. Each processing unit is assigned to exactly one process operation, and each process operation is thus associated with one or more processing units. This association determines which tools (determined from the processing unit) are required in each operation. Since each process operation corresponds to one press or to one station in a press, this association is needed to configure the press or station. Conversely, such a configuration needs to be checked whether it is feasible. If it is not, the association can be changed, that is, the processing units can be assigned to the operations in a different manner. This can lead to an iterative optimization process, with one of possibly several optimization goals being the minimization of the number of operations.